The primary objective of this contract will be to provide large quantities of the primate viruses. These viruses to be provided as follows: simian sarcoma virus, gibbon ape lymphosarcoma virus, and Mason-Pfizer virus. The Contractor must be able to provide a minimum of fifty (50) liters per week of primate viruses in human cells at the following minimum virus titers: simian sarcoma virus, 2 x 10-18 virus particle/ml; and gibbon ape leukemia virus, 5 x 10-7 virus particle/ml.